clk: renesas: r8a7796: Add R8A77961 CPG/MSSR support

Add support for the R-Car M3-W+ (R8A77961) SoC.
R-Car M3-W+ is very similar to R-Car M3-W (R8A77960), which allows for
both SoCs to share a driver.

Based on Linux commit 2ba738d56db4 ("clk: renesas: r8a7796: Add R8A77961
CPG/MSSR support")

Reviewed-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Signed-off-by: Hai Pham <hai.pham.ud@renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
diff --git a/drivers/clk/renesas/Kconfig b/drivers/clk/renesas/Kconfig
index 939aa8d..a538e7e 100644
--- a/drivers/clk/renesas/Kconfig
+++ b/drivers/clk/renesas/Kconfig
@@ -85,6 +85,12 @@
 	help
 	  Enable this to support the clocks on Renesas R8A77960 SoC.
 
+config CLK_R8A77961
+	bool "Renesas R8A77961 clock driver"
+	depends on CLK_RCAR_GEN3
+	help
+	  Enable this to support the clocks on Renesas R8A77961 SoC.
+
 config CLK_R8A77965
 	bool "Renesas R8A77965 clock driver"
 	depends on CLK_RCAR_GEN3